package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.ObjectUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryShopById(Long id) {
        Shop shop = getById(id);
        // 缓存穿透
      /* Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class,
                this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);*/

        // 逻辑过期 解决缓存击穿
//        Shop shop = queryWithLogicalExpire(id);
//        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class,
//                this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        // 互斥锁 解决缓存击穿
//        Shop shop = queryWithMutex(id);
//        Shop shop = cacheClient.queryWithMutex(CACHE_SHOP_KEY, id, Shop.class,
//                this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        // 7.返回数据
        return Result.ok(shop);
    }

    /**
     * 创建线程池
     */
//    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 逻辑过期解决缓存击穿
     *
     * @param id
     * @return
     */
    /*
    private Shop queryWithLogicalExpire(Long id) {
        // 1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        if (StrUtil.isBlank(shopJson)) {
            // 2.未命中 直接返回
            return null;
        }
        // 3.命中 需要判断过期时间 把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //4.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.未过期 直接返回店铺信息
            return shop;
        }
        //6.已过期 需要缓存重建
        //6.1尝试获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean lock = tryLock(lockKey);
        //6.1.1判断是否获取锁成功
        if (lock) {
            //获取锁成功，再次检测redis是否存在数据
            shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
            if (StrUtil.isBlank(shopJson)) {
                // 2.未命中 直接返回
                return null;
            }
            //  6.2获取锁成功 开启独立线程 实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    // 缓存重建
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    // 释放锁
                    unlock(lockKey);
                }
            });

        }
        // 6.3失败 返回过期的店铺信息
        return shop;
    }
    */

    /**
     * 互斥锁解决缓存击穿
     * queryWithMutex(Long id)
     * @param id
     * @return
     */
    /*
    private Shop queryWithMutex(Long id) {
        // 1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);

        if (StrUtil.isNotBlank(shopJson)) {
            // 2.命中 直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        // 3.判断是否为空值
        if ("".equals(shopJson)) {
            return null;
        }
        //缓存重建
        //4.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2判断是否获取成功
            if (!isLock) {
                //4.3获取失败，休眠重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4成功 再次检测redis是否存在数据
            //4.4.1存在：
            shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
            if (StrUtil.isNotBlank(shopJson)) {
                // 2.命中 直接返回
                shop = JSONUtil.toBean(shopJson, Shop.class);
                return shop;
            }
            //4.4.2不存在： 根据id查询数据库
            shop = getById(id);
            // 模拟重建延时
//            Thread.sleep(200);
            //5.数据库中也不存在  返回错误信息
            if (ObjectUtil.isEmpty(shop)) {
                // 将空值写入redis
                stringRedisTemplate.opsForValue()
                        .set(CACHE_SHOP_KEY + id, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                // 数据库中没有数据  返回错误信息
                return null;
            }
            //6.数据库中存在 则写入redis缓存  （将shop转为json格式）
            stringRedisTemplate.opsForValue()
                    .set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.释放互斥锁
            unlock(lockKey);
        }
        //8.返回数据
        return shop;
    }
    */

    /**
     * 防止 缓存穿透代码
     * queryWithPassThrough(Long id)
     * @param id
     * @return
     */
    /*
    private Shop queryWithPassThrough(Long id) {
        // 1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);

        if (StrUtil.isNotBlank(shopJson)) {
            // 2.命中 直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if ("".equals(shopJson)) {
            return null;
        }
        // 3.未命中 查数据库
        Shop shop = getById(id);
        if (ObjectUtil.isEmpty(shop)) {
            // 将空值写入redis
            stringRedisTemplate.opsForValue()
                    .set(CACHE_SHOP_KEY + id, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            // 4.数据库中没有数据  返回错误信息
            return null;
        }
        // 5.数据库中有数据
        // 6.写入redis缓存  （将shop转为json格式）
        stringRedisTemplate.opsForValue()
                .set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 7.返回数据
        return shop;
    }
   */

    /**
     * 获取锁
     *
     * @param key
     * @return
     */
    private boolean tryLock(String key) {
        Boolean lock = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(lock);
    }

    /**
     * 释放锁
     *
     * @param key
     */
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    // 将shop数据写入redis并设置逻辑过期时间  （缓存重建）
    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        // 模拟重建过程
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //是否根据坐标查询
        if (x == null || y == null) {
            //不需要坐标查询 按数据查询  根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        //查询redis，按照距离排序做分页  shopId  distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands
                                .GeoSearchCommandArgs.newGeoSearchArgs()
                                .includeDistance()
                                .limit(end)
                );

        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        //解析数据出 id
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();

        if(list.size()<=from){
            return Result.ok(Collections.emptyList());
        }

        //截取 从from 到end 的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });

        //根据id查询店铺
        String idStr = StrUtil.join(",", ids);
        List<Shop> shopList = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shopList) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //返回
        return Result.ok(shopList);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 1.更新数据库
        updateById(shop);
        // 2. 删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
}
